Replacement motor smells of smoke, less than 30 days after original smoked. WTH?

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MitchRyan912

MitchRyan912

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Jul 21, 2015
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Madison, WI
So my original pool pump, a Waterway SMF-110, went up I smoke about a month ago, so I replaced the motor and kept the wet end. The new pump had been running fine, but was down for a few days while I re-piped some plumbing. Shortly after getting it all hooked up again, it started to sound funny and started to smell like smoke.

I'm at a loss as to figuring out What The Heck has caused two separate motors to smoke in less than a month?
 
You may need to double check the wiring. I read one of your previous posts stating you wired a timer control to a 2 speed motor? If both speeds were being energized simultaneously, that would make quick work of frying the motor.

I would test the total external pressure in and out of the pump, when you get it up and running again.
Overloading a smaller motor with a larger impeller would also cause a burnout.
 
The previous motor was a single speed that ran 24/7.

I didn't change the impeller on the wet end, since the THP rating was the same. New one was .75 HP x 1.6 SF = 1.25 THP. Old motor was 1 HP x 1.25 HP = 1.25 THP. Should I have done so?

I just check voltage at the panel in the house and at the motor. Same voltage, so noticable voltage drop on the wiring. I'm about to unhook the pump from the timer and take apart the pump to see if anything is blocking the impeller from moving.

The only major difference between the pumps is that I just converted a deep end vac line to be able to be used as either a return or a vac line, based on how two 3-way diverter valves are set.
 
The motor is 240v only.

I checked it with the motor running, and there was no noticeable change that I could see with an analog voltmeter. I don't have a meter that can check current draw, so I can't tell what's going on there.
 
Yes, it runs hot, but it seemed hotter than normal yesterday. I don't have an ammeter, so I can't check that. I don't know about the impeller. I was told by mas985 on another forum that my impeller is likely fine:

"As for the impeller, it depends on the service factor of your current pump motor. If the current service factor is 1.25 or lower, then the impeller is fine. Diffuser would not change either way."
Click to expand...
SF of old pump was 1.25. SF of new pump is 1.6.

FWIW, it seems like we have very similar sized pools, yet we have very different sized motors as far as total HP (1.25 vs .75). What size pipe are you running and how long are your lines? I've got 1.5" flex pipe and I think it was about 30 and 45 feet from the pump to the 2 suction lines, with about 60 feet to the shallow end return.
 
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MitchRyan912 said:
FWIW, it seems like we have very similar sized pools, yet we have very different sized motors as far as total HP (1.25 vs .75). What size pipe are you running and how long are your lines? I've got 1.5" flex pipe and I think it was about 30 and 45 feet from the pump to the 2 suction lines, with about 60 feet to the shallow end return.
Click to expand...

I have 1.5" schedule 40 PVC and my lines are about 75' to the shallow end. Filter pressure runs about 8 psi.

My approach to troubleshooting would be based on the fact that something common to both pumps is the trouble. Assuming the motor spins freely, I'd really be focused on a electrical supply issue that forces the motor to draw too many amps.... at least, first... then?
 
ewkearns said:
I have 1.5" schedule 40 PVC and my lines are about 75' to the shallow end. Filter pressure runs about 8 psi.

My approach to troubleshooting would be based on the fact that something common to both pumps is the trouble. Assuming the motor spins freely, I'd really be focused on a electrical supply issue that forces the motor to draw too many amps.... at least, first... then?
Click to expand...

As a former electrician, my guess would have been that a 60' run of 12 gauge solid wire might not have been sufficient, but it's been fine for 30+ years and the previous 2 owners of the home. I'd love to upgrade the run to the shed in back, but that means upgrading the main house panel in order to do so. That's a $4000+ project to do all that, and as much as I would LOVE to have our house panel upgraded, that's not in the cards anytime soon.

I also suspect that the flex pipe may have been compromised somewhere along the way. There a "privacy fence" of arbor vitae trees that were planted right over the line where the pipes run. Any one root might grow towards a round pipe and get deflected away from it, but there are tons of roots and about 15-20 trees in the area where the pipes run. I may need to find someone with a snake to see if the skimmer line is clogged up, as there is a noticable drop in filter pressure when I would only have that single line running. It was about a 2 psi difference between running the skimmer only vs the vac line only.
 
Would throwing on the pressure gauge only tell me anything useful, or should I go ahead and order up a vacuum gauge from Amazon and wait a couple days to test the pump again, with both gauges installed? I got a pressure gauge from my work today, but they don't have a vacuum gauge (nor does anyone in town.)
 
Their mobile site is incredibly difficult to navigate, and where/how I was searching wasn't showing any vacuum gauges. Now that I search for the brand I bought from Amazon, I can find them on Grainger's site. However, they're not available for pickup until Tuesday, so it's a moot point now (plus they're twice the cost compare to Amazon!)

Other than working on the chemicals for the pool, I'm taking a break from the pool until those gauges get here. I'll post the results once the vac gauge arrives.
 
I suspect there is something wrong with the motor that's causing this problem. Low speed no longer works at all, and high speed just isn't enough to get the pump close to prime. :(

It's been less than 30 days, so thankfully there is a new motor on its way.
 
If you still have the old motor, what was the direction? CW or CCW?
Looks like the new one is CCW but can't find the literature providing the old motor's direction.

With that kind of current, it sound like you have 120v supply voltage.
Also, it looks like the new motor may be a psc. So if it is, it uses a runcapacitor that remains in the circuit. Have you checked the capacitor?
You, would have unusually high run winding current with a bad capacitor.
Before connecting that new motor, I would definitely check over all of the wiring, especially making sure the timer is not applying power to both speeds at the same time.
 

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